1. Field of the Invention
The present invention relates to a color gamut conversion device, a color gamut conversion method, and a color gamut conversion program for converting a color gamut of a color space.
2. Description of the Related Art
In a general image system, a color space is defined according to the sRGB (standard RGB) standard that is an international standard. Along with recent improvement in instrument performance, a color gamut that is a color expression range tends to expand. For example, the color gamuts of liquid crystal displays using a LED with high color purity of luminescent color as a backlight or those of projectors using a laser light source have become considerably wider as compared with the conventional ones. Under such circumstances, studies on the wide color gamut color system of Super Hi-Vision are being conducted.
In various devices, color gamut conversion for converting a wide color gamut image signal into a narrow color gamut image signal (see, for example, Patent Documents 1 and 2) or color gamut conversion for converting a narrow color gamut image signal into a wide color gamut image signal is performed. Among the latter color gamut conversion, there is a method of linearly expanding a color gamut according to a saturation value or an output color gamut width value (see, for example, Patent Document 3), but there is no process to change the extent of expansion in accordance with lightness or hue. Additionally, if it is attempted to adjust a color gamut for all lightness and all hues with respect to an image acquired by a camera with a narrow color gamut, it is impossible to expand a color gamut that can be expanded, and It is difficult to fully utilize the color gamut.